<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .first li:nth-child(1) {
        background-color: #ccc;
    }

    li {
        padding-left: 0;
    }
</style>

<body>
    <ul class="first">
        <li>1</li>
        <li>1</li>
        <li>1</li>
        <li>1</li>
        <li>1</li>
    </ul>
</body>

</html>